ldso.c

Axis 221 camera embedded programing interface

/* vi: set sw=4 ts=4: */
/*
 * Program to load an ELF binary on a linux system, and run it
 * after resolving ELF shared library symbols
 *
 * Copyright (C) 2000-2004 by Erik Andersen <[e-mail]>
 * Copyright (c) 1994-2000 Eric Youngdale, Peter MacDonald,
 *				David Engel, Hongjiu Lu and Mitch D'Souza
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. The name of the above contributors may not be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "ldso.h"
#include "unsecvars.h"

#define ALLOW_ZERO_PLTGOT

/* Pull in the value of _dl_progname */
#include "dl-progname.h"

/* Global variables used within the shared library loader */
char *_dl_library_path         = 0;	/* Where we look for libraries */
char *_dl_preload              = 0;	/* Things to be loaded before the libs */
char *_dl_ldsopath             = 0;	/* Location of the shared lib loader */
int _dl_secure                 = 1;	/* Are we dealing with setuid stuff? */
int _dl_errno                  = 0;	/* We can't use the real errno in ldso */
size_t _dl_pagesize            = 0;	/* Store the page size for use later */
struct r_debug *_dl_debug_addr = NULL;	/* Used to communicate with the gdb debugger */
void *(*_dl_malloc_function) (size_t size) = NULL;

#ifdef __SUPPORT_LD_DEBUG__
char *_dl_debug           = 0;
char *_dl_debug_symbols   = 0;
char *_dl_debug_move      = 0;
char *_dl_debug_reloc     = 0;
char *_dl_debug_detail    = 0;
char *_dl_debug_nofixups  = 0;
char *_dl_debug_bindings  = 0;
int   _dl_debug_file      = 2;
#endif

#include "dl-startup.c"
/* Forward function declarations */
static int _dl_suid_ok(void);

/*
 * This stub function is used by some debuggers.  The idea is that they
 * can set an internal breakpoint on it, so that we are notified when the
 * address mapping is changed in some way.
 */
void _dl_debug_state(void)
{
}

static unsigned char *_dl_malloc_addr = 0;	/* Lets _dl_malloc use the already allocated memory page */
static unsigned char *_dl_mmap_zero   = 0;	/* Also used by _dl_malloc */

#if defined (__SUPPORT_LD_DEBUG__)
static void debug_fini (int status, void *arg)
{
	(void)status;
	_dl_dprintf(_dl_debug_file,"\ncalling fini: %s\n\n", (const char*)arg);
}
#endif

void _dl_get_ready_to_run(struct elf_resolve *tpnt, unsigned long load_addr,
			  Elf32_auxv_t auxvt[AT_EGID + 1], char **envp,
			  char **argv)
{
	ElfW(Phdr) *ppnt;
	Elf32_Dyn *dpnt;
	char *lpntstr;
	int i, nlist, goof = 0, unlazy = 0, trace_loaded_objects = 0;
	struct elf_resolve **init_fini_list;
	struct dyn_elf *rpnt;
	struct elf_resolve *tcurr;
	struct elf_resolve *tpnt1;
	struct elf_resolve app_tpnt_tmp;
	struct elf_resolve *app_tpnt = &app_tpnt_tmp;
	struct r_debug *debug_addr;
	unsigned long *lpnt;
	int (*_dl_atexit) (void *);
	unsigned long *_dl_envp;		/* The environment address */
	ElfW(Addr) relro_addr = 0;
	size_t relro_size = 0;
#if defined (__SUPPORT_LD_DEBUG__)
	int (*_dl_on_exit) (void (*FUNCTION)(int STATUS, void *ARG),void*);
#endif

#ifdef __SUPPORT_LD_DEBUG_EARLY__
	/* Wahoo!!! */
	SEND_STDERR("Cool, we managed to make a function call.\n");
#endif

	/* Store the page size for later use */
	_dl_pagesize = (auxvt[AT_PAGESZ].a_un.a_val) ? (size_t) auxvt[AT_PAGESZ].a_un.a_val : PAGE_SIZE;
	/* Make it so _dl_malloc can use the page of memory we have already
	 * allocated.  We shouldn't need to grab any more memory.  This must
	 * be first since things like _dl_dprintf() use _dl_malloc()...
	 */
	_dl_malloc_addr = (unsigned char *)_dl_pagesize;
	_dl_mmap_zero = 0;

	/* Now we have done the mandatory linking of some things.  We are now
	 * free to start using global variables, since these things have all
	 * been fixed up by now.  Still no function calls outside of this
	 * library, since the dynamic resolver is not yet ready.
	 */
	if (argv[0]) {
		_dl_progname = argv[0];
	}

	/* Start to build the tables of the modules that are required for
	 * this beast to run.  We start with the basic executable, and then
	 * go from there.  Eventually we will run across ourself, and we
	 * will need to properly deal with that as well.
	 */
	rpnt = NULL;
	if (_dl_getenv("LD_BIND_NOW", envp))
		unlazy = RTLD_NOW;

	/* At this point we are now free to examine the user application,
	 * and figure out which libraries are supposed to be called.  Until
	 * we have this list, we will not be completely ready for dynamic
	 * linking.
	 */

	/* Find the runtime load address of the main executable.  This may be
	 * different from what the ELF header says for ET_DYN/PIE executables.
	 */
	{
		int i;
		ElfW(Phdr) *ppnt = (ElfW(Phdr) *) auxvt[AT_PHDR].a_un.a_ptr;

		for (i = 0; i < auxvt[AT_PHNUM].a_un.a_val; i++, ppnt++)
			if (ppnt->p_type == PT_PHDR) {
				app_tpnt->loadaddr = (ElfW(Addr)) (auxvt[AT_PHDR].a_un.a_val - ppnt->p_vaddr);
				break;
			}

#ifdef __SUPPORT_LD_DEBUG_EARLY__
		if (app_tpnt->loadaddr) {
			SEND_STDERR("Position Independent Executable: app_tpnt->loadaddr=");
			SEND_ADDRESS_STDERR(app_tpnt->loadaddr, 1);
		}
#endif
	}

	/*
	 * This is used by gdb to locate the chain of shared libraries that are
	 * currently loaded.
	 */
	debug_addr = _dl_malloc(sizeof(struct r_debug));
	_dl_memset(debug_addr, 0, sizeof(struct r_debug));

	ppnt = (ElfW(Phdr) *) auxvt[AT_PHDR].a_un.a_ptr;
	for (i = 0; i < auxvt[AT_PHNUM].a_un.a_val; i++, ppnt++) {
		if (ppnt->p_type == PT_GNU_RELRO) {
			relro_addr = ppnt->p_vaddr;
			relro_size = ppnt->p_memsz;
		}
		if (ppnt->p_type == PT_DYNAMIC) {
			dpnt = (Elf32_Dyn *) (ppnt->p_vaddr + app_tpnt->loadaddr);
			_dl_parse_dynamic_info(dpnt, app_tpnt->dynamic_info, debug_addr);
#ifndef __FORCE_SHAREABLE_TEXT_SEGMENTS__
			/* Ugly, ugly.  We need to call mprotect to change the
			 * protection of the text pages so that we can do the
			 * dynamic linking.  We can set the protection back
			 * again once we are done.
			 */
#ifdef __SUPPORT_LD_DEBUG_EARLY__
			SEND_STDERR("calling mprotect on the application program\n");
#endif
			/* Now cover the application program. */
			if (app_tpnt->dynamic_info[DT_TEXTREL]) {
				ppnt = (ElfW(Phdr) *) auxvt[AT_PHDR].a_un.a_ptr;
				for (i = 0; i < auxvt[AT_PHNUM].a_un.a_val; i++, ppnt++) {
					if (ppnt->p_type == PT_LOAD && !(ppnt->p_flags & PF_W))
						_dl_mprotect((void *) ((ppnt->p_vaddr + app_tpnt->loadaddr) & PAGE_ALIGN),
							     ((ppnt->p_vaddr + app_tpnt->loadaddr) & ADDR_ALIGN) +
							     (unsigned long) ppnt->p_filesz,
							     PROT_READ | PROT_WRITE | PROT_EXEC);
				}
			}
#endif

#ifndef ALLOW_ZERO_PLTGOT
			/* make sure it's really there. */
			if (app_tpnt->dynamic_info[DT_PLTGOT] == 0)
				continue;
#endif
			/* OK, we have what we need - slip this one into the list. */
			app_tpnt = _dl_add_elf_hash_table(_dl_progname, (char *)app_tpnt->loadaddr,
					app_tpnt->dynamic_info, ppnt->p_vaddr + app_tpnt->loadaddr, ppnt->p_filesz);
			_dl_loaded_modules->libtype = elf_executable;
			_dl_loaded_modules->ppnt = (ElfW(Phdr) *) auxvt[AT_PHDR].a_un.a_ptr;
			_dl_loaded_modules->n_phent = auxvt[AT_PHNUM].a_un.a_val;
			_dl_symbol_tables = rpnt = (struct dyn_elf *) _dl_malloc(sizeof(struct dyn_elf));
			_dl_memset(rpnt, 0, sizeof(struct dyn_elf));
			rpnt->dyn = _dl_loaded_modules;
			app_tpnt->rtld_flags = unlazy | RTLD_GLOBAL;
			app_tpnt->usage_count++;
			app_tpnt->symbol_scope = _dl_symbol_tables;
			lpnt = (unsigned long *) (app_tpnt->dynamic_info[DT_PLTGOT] + app_tpnt->loadaddr);
#ifdef ALLOW_ZERO_PLTGOT
			if (lpnt)
#endif
				INIT_GOT(lpnt, _dl_loaded_modules);
		}

		/* OK, fill this in - we did not have this before */
		if (ppnt->p_type == PT_INTERP) {
			int readsize = 0;
			char *pnt, *pnt1, buf[1024];

			tpnt->libname = _dl_strdup((char *) ppnt->p_offset +
					(auxvt[AT_PHDR].a_un.a_val & PAGE_ALIGN));

			/* Determine if the shared lib loader is a symlink */
			_dl_memset(buf, 0, sizeof(buf));
			readsize = _dl_readlink(tpnt->libname, buf, sizeof(buf));
			if (readsize > 0 && readsize < (int)(sizeof(buf)-1)) {
				pnt1 = _dl_strrchr(buf, '/');
				if (pnt1 && buf != pnt1) {
#ifdef __SUPPORT_LD_DEBUG_EARLY__
					_dl_dprintf(_dl_debug_file,
						    "changing tpnt->libname from '%s' to '%s'\n",
						    tpnt->libname, buf);
#endif
					tpnt->libname = _dl_strdup(buf);
				}
			}

			/* Store the path where the shared lib loader was found
			 * for later use
			 */
			pnt = _dl_strdup(tpnt->libname);
			pnt1 = _dl_strrchr(pnt, '/');
			if (pnt != pnt1) {
				*pnt1 = '\0';
				_dl_ldsopath = pnt;
			} else {
				_dl_ldsopath = tpnt->libname;
			}
#ifdef __SUPPORT_LD_DEBUG_EARLY__
			_dl_dprintf(_dl_debug_file, "Lib Loader:\t(%x) %s\n",
				    tpnt->loadaddr, tpnt->libname);
#endif
		}
	}
	app_tpnt->relro_addr = relro_addr;
	app_tpnt->relro_size = relro_size;

	/* Now we need to figure out what kind of options are selected.
	 * Note that for SUID programs we ignore the settings in
	 * LD_LIBRARY_PATH.
	 */
	if ((auxvt[AT_UID].a_un.a_val == -1 && _dl_suid_ok()) ||
	    (auxvt[AT_UID].a_un.a_val != -1 &&
	     auxvt[AT_UID].a_un.a_val == auxvt[AT_EUID].a_un.a_val &&
	     auxvt[AT_GID].a_un.a_val == auxvt[AT_EGID].a_un.a_val)) {
		_dl_secure = 0;
		_dl_preload = _dl_getenv("LD_PRELOAD", envp);
		_dl_library_path = _dl_getenv("LD_LIBRARY_PATH", envp);
	} else {
		static const char unsecure_envvars[] =
#ifdef EXTRA_UNSECURE_ENVVARS
			EXTRA_UNSECURE_ENVVARS
#endif
			UNSECURE_ENVVARS;
		const char *nextp;
		_dl_secure = 1;

		nextp = unsecure_envvars;
		do {
			_dl_unsetenv (nextp, envp);
			/* We could use rawmemchr but this need not be fast.  */
			nextp = (char *) _dl_strchr(nextp, '\0') + 1;
		} while (*nextp != '\0');
		_dl_preload = NULL;
		_dl_library_path = NULL;
	}

#ifdef __SUPPORT_LD_DEBUG__
	_dl_debug = _dl_getenv("LD_DEBUG", envp);
	if (_dl_debug) {
		if (_dl_strstr(_dl_debug, "all")) {
			_dl_debug_detail = _dl_debug_move = _dl_debug_symbols
				= _dl_debug_reloc = _dl_debug_bindings = _dl_debug_nofixups = (void*)1;
		} else {
			_dl_debug_detail   = _dl_strstr(_dl_debug, "detail");
			_dl_debug_move     = _dl_strstr(_dl_debug, "move");
			_dl_debug_symbols  = _dl_strstr(_dl_debug, "sym");
			_dl_debug_reloc    = _dl_strstr(_dl_debug, "reloc");
			_dl_debug_nofixups = _dl_strstr(_dl_debug, "nofix");
			_dl_debug_bindings = _dl_strstr(_dl_debug, "bind");
		}
	}

	{
		const char *dl_debug_output;

		dl_debug_output = _dl_getenv("LD_DEBUG_OUTPUT", envp);

		if (dl_debug_output) {
			char tmp[22], *tmp1, *filename;
			int len1, len2;

			_dl_memset(tmp, 0, sizeof(tmp));
			tmp1 = _dl_simple_ltoa( tmp, (unsigned long)_dl_getpid());

			len1 = _dl_strlen(dl_debug_output);
			len2 = _dl_strlen(tmp1);

			filename = _dl_malloc(len1+len2+2);

			if (filename) {
				_dl_strcpy (filename, dl_debug_output);
				filename[len1] = '.';
				_dl_strcpy (&filename[len1+1], tmp1);

				_dl_debug_file= _dl_open(filename, O_WRONLY|O_CREAT, 0644);
				if (_dl_debug_file < 0) {
					_dl_debug_file = 2;
					_dl_dprintf (2, "can't open file: '%s'\n",filename);
				}
			}
		}
	}
#endif

	if (_dl_getenv("LD_TRACE_LOADED_OBJECTS", envp) != NULL) {
		trace_loaded_objects++;
	}

#ifndef __LDSO_LDD_SUPPORT__
	if (trace_loaded_objects) {
		_dl_dprintf(_dl_debug_file, "Use the ldd provided by uClibc\n");
		_dl_exit(1);
	}
#endif

	/*
	 * OK, fix one more thing - set up debug_addr so it will point
	 * to our chain.  Later we may need to fill in more fields, but this
	 * should be enough for now.
	 */
	debug_addr->r_map = (struct link_map *) _dl_loaded_modules;
	debug_addr->r_version = 1;
	debug_addr->r_ldbase = load_addr;
	debug_addr->r_brk = (unsigned long) &_dl_debug_state;
	_dl_debug_addr = debug_addr;

	/* Notify the debugger we are in a consistant state */
	_dl_debug_addr->r_state = RT_CONSISTENT;
	_dl_debug_state();

	/* OK, we now have the application in the list, and we have some
	 * basic stuff in place.  Now search through the list for other shared
	 * libraries that should be loaded, and insert them on the list in the
	 * correct order.
	 */

	_dl_map_cache();

	if (_dl_preload) {
		char c, *str, *str2;

		str = _dl_preload;
		while (*str == ':' || *str == ' ' || *str == '\t')
			str++;

		while (*str) {
			str2 = str;
			while (*str2 && *str2 != ':' && *str2 != ' ' && *str2 != '\t')
				str2++;
			c = *str2;
			*str2 = '\0';

			if (!_dl_secure || _dl_strchr(str, '/') == NULL) {
				if ((tpnt1 = _dl_check_if_named_library_is_loaded(str, trace_loaded_objects))) {
					tpnt1->usage_count++;
					goto next_lib;
				}

#if defined (__SUPPORT_LD_DEBUG__)
				if(_dl_debug)
					_dl_dprintf(_dl_debug_file,
						    "\tfile='%s';  needed by '%s'\n",
						    str, _dl_progname);
#endif

				tpnt1 = _dl_load_shared_library(_dl_secure, &rpnt, NULL, str, trace_loaded_objects);
				if (!tpnt1) {
#ifdef __LDSO_LDD_SUPPORT__
					if (trace_loaded_objects)
						_dl_dprintf(1, "\t%s => not found\n", str);
					else
#endif
					{
						_dl_dprintf(2, "%s: can't load " "library '%s'\n", _dl_progname, str);
						_dl_exit(15);
					}
				} else {
					tpnt1->rtld_flags = unlazy | RTLD_GLOBAL;

#ifdef __SUPPORT_LD_DEBUG_EARLY__
					_dl_dprintf(_dl_debug_file,
						    "Loading:\t(%x) %s\n",
						    tpnt1->loadaddr,
						    tpnt1->libname);
#endif

#ifdef __LDSO_LDD_SUPPORT__
					if (trace_loaded_objects &&
					    tpnt1->usage_count == 1) {
						/* This is a real hack to make
						 * ldd not print the library
						 * itself when run on a
						 * library.
						 */
						if (_dl_strcmp(_dl_progname, str) != 0)
							_dl_dprintf(1, "\t%s => %s (%x)\n", str, tpnt1->libname,
								    (unsigned)tpnt1->loadaddr);
					}
#endif
				}
			}

next_lib:
			*str2 = c;
			str = str2;
			while (*str == ':' || *str == ' ' || *str == '\t')
				str++;
		}
	}

#ifdef __LDSO_PRELOAD_FILE_SUPPORT__
	do {
		struct stat st;
		char *preload;
		int fd;
		char c, *cp, *cp2;

		if (_dl_stat(LDSO_PRELOAD, &st) || st.st_size == 0) {
			break;
		}

		if ((fd = _dl_open(LDSO_PRELOAD, O_RDONLY, 0)) < 0) {
			_dl_dprintf(2, "%s: can't open file '%s'\n",
				    _dl_progname, LDSO_PRELOAD);
			break;
		}